evolution: the effect of pressure and heat (Introduction)

by David Turell , Monday, October 28, 2024, 19:44 (27 days ago) @ David Turell

Creates unexpected events:

https://www.newscientist.com/article/2453548-weird-microbes-could-help-rewrite-the-orig...

"Compressing a type of single-celled microorganism makes it develop into a multicellular tissue-like structure with different cell types. This suggests that pressure can help drive key evolutionary leaps, such as the emergence of multicellularity.

"he organism is a type of archaea, one of the three domains of life, along with bacteria and eukaryotes. The eukaryotes are organisms with cells containing a nucleus and include animals and plants. Archaea lack a nucleus, so were originally mistaken for bacteria, but are now thought to share a common ancestor with eukaryotes.

"Unlike most organisms, archaea also lack a stiff cell wall, a trait they share with animal cells. Lacking a cell wall gives animal cells flexibility and allows them to develop markedly different shapes. They can also change cell type in response to mechanical forces. Archaea are also able to form complex shapes and interact with each other, but little is known about how they react to such forces.

"To find out more, Alex Bisson at Brandeis University in Massachusetts and his team squashed a salt-loving archaea called Haloferax volcanii under jelly pads, mimicking the forces they experience in their natural habitats – and saw something completely unexpected.

"The cells grew and started making multiple copies of their genomes. When the tension in the cells’ membranes reached a critical point, new membranes grew between these genomes to create individual cells that were genetic clones of the original cell, forming a mound-shaped multicellular tissue.

"The team tested 52 other similar species and found that more than 60 per cent of them formed tissues. This kind of cell division is also seen in a wide range of multicellular eukaryotes, such as during chick embryo development.

"Next, the team zapped individual cells in the tissues with a laser to test whether they were connected to each other. When a cell was killed by the laser, neighbouring cells moved towards the wound, as cells in animal tissues called epithelium do.

"This suggests that cells in the archaeal tissues are tethered together, just as they are in animal or plant tissues. Archaea lack the genes that animal and plant cells use for these tethers, so they have probably evolved their own method of doing this, says Bisson.

"The cells in the tissues also developed into two distinct types. Those around the edge – where less pressure was applied – were flat, while those in the middle formed an angular structure resembling a scutoid, a shape first identified in animal epithelial cells in 2018.

"This shows the advantages of exploring the biomechanical properties of cells across domains of life – rather than just genetic information – when studying evolution, says Bisson.

“'The idea that gene novelty alone governs evolutionary leaps now seems insufficient,” says Omaya Dudin at the University of Geneva in Switzerland. “Physical and mechanical factors are emerging as key players in orchestrating complex biological innovations in single-celled creatures.'”

Comment: an exciting finding that physical forces can play such a role, which means their DNA is coded for the proper responses. Of course, this means they could have been designed.